The effect of aspect ratio and content of steel fiber on fracture energy of concrete

This thesis investigates the effect of steel fiber aspect ratio and content on the fracture energy of concrete. In the research, it was aimed to use steel fiber locally produced and steel fiber content preferred in practice. For this purpose, specimens were produced by substituting steel fibers with a aspect ratio of 65 and 80 at 15 kg/m3, 20 kg/m3 and 25 kg/m3 into concrete. In the experimental study, C30/37 concrete class and 15 cm slump value were taken as reference. Workability and fresh unit weight tests were performed on fresh concretes. Compressive and splitting tensile strength tests were performed on hardened steel fiber reinforced specimens, respectively. 150mmx150mmx150mm cube specimens and 100mmx200mm cylinder specimens were used for compressive and splitting tensile tests, respectively. In addition, flexural tests were performed on notched prismatic beam specimens with dimensions of 150mmx150mmx600mm to determine the flexural strength of the specimens. From the load-deflection curves obtained from the flexural test, the fracture energies of the SFRCs were calculated. Based on the test results, increases in compressive, splitting, tensile and flexural strengths were obtained with increasing steel fiber content. The increases in flexural and splitting strengths were higher compared to compressive strength. Significant increases were obtained in the fracture energies of SFRCs beams depending on the steel fiber aspect ratio and content.